Power conservation is a major design objective, even in high performance circuits. High speed embedded static random access memories (SRAMs) in current superscalar processors are struggling to keep up with the processors due to rapidly decreasing processor cycle times and to restrictions on power consumption. As processor designs increase in both the degree of scalarity (number of execution units) and word size, embedded cache SRAMs are both limiting processor speed (or decreasing throughput as latency increases) and contributing significantly to such a chip's power consumption.
The limitations associated with SRAMs are primarily due to conventional SRAM design. A SRAM typically comprises an array of cells. The cells in each column of the array are coupled by two lines, known as bit lines, to a sense amplifier, which reads the information stored in the cells by sensing a small differential voltage across the bit-line pair.
Traditional SRAM designs create several power consumption issues. First, wide line sizes comprising the SRAM circuits greatly increase power consumption by requiring many more sense amplifiers, and also take away a design freedom. Second, sense amplifiers dissipate a significant amount of power because the transistors used in differential amplifiers must be placed into a linear operating mode until the voltage difference across the bit-line pair exceeds a predetermined threshold. In addition, due to architectural restrictions, sense amplifiers are becoming more difficult to design; and the traditional method of increasing speed in a SRAM is to increase the power supplied to the sense amplifier.
Accordingly, what is needed is a system and method for providing a RAM structure that uses a sense approach that both increases performance and decreases power consumption. The present invention addresses such a need.